Priority encoder behavior with multiple active inputs If two input lines are active simultaneously on a priority encoder, which input value is represented on the binary output?

Introduction / Context:
A priority encoder resolves conflicts when more than one input is asserted. It outputs the code for the highest-priority (commonly the highest-index) active input and typically provides additional flags (e.g., valid output). Understanding priority behavior prevents ambiguity in interrupt controllers, keyboard encoders with rollover, and bus request arbiters.

Given Data / Assumptions:

• Standard priority convention: higher-numbered input has higher priority.
• Two inputs become active at the same time.
• Device asserts only one output code and may raise a “valid” flag.

Concept / Approach:

By definition, a priority encoder selects the highest-priority asserted line. Therefore, if inputs i and j are active and i > j, the binary output corresponds to i. Lower-priority inputs are effectively masked.

Step-by-Step Solution:

Verification / Alternative check:

Datasheets for devices like 74HC147 (10-line to 4-line priority encoder) show truth tables where higher inputs dominate when multiple are active.

Why Other Options Are Wrong:

Lower value: contradicts the “priority” specification.

Neither/both: real priority encoders are designed to deliver a single, unambiguous code when multiple inputs are active.

Common Pitfalls:

Forgetting to synchronize inputs to avoid metastability; misunderstanding active-low conventions (some encoders use active-low inputs/outputs, but priority still favors the higher-numbered line).

Final Answer:

the higher value